There are many medical conditions for which it is desirable to draw a blood sample from a patient for analysis. For example, in the case of certain communicable diseases, a blood sample drawn from a patient may be analyzed for the presence of a blood borne pathogen. Alternatively, in the case of diabetes, blood samples drawn periodically from a patient may be used to monitor blood sugar levels.
Blood samples taken from a patient for blood sugar monitoring are typically obtained by piercing the skin of the patient using a lancing instrument (also referred to herein as a lancing device). A lancing instrument typically includes a body and a lancet. The body is typically adapted to be held by the user, the lancet being coupled to the body and being adapted to penetrate through the epidermis (the outermost layer of the skin) of the patient and into the dermis (the layer of skin directly beneath the epidermis) which is replete with capillary beds. The puncture of one or more capillaries by the lancet generates a sample of blood which exits through the incision in the patient's skin.
In some lancing devices, the lancet is fixedly coupled to the body. In other lancing devices, the lancet is adapted to be moved, when actuated, from a retracted position in which the lancet tip is disposed within the body to an extended position in which the lancet tip extends beyond the body. Typically, the movement of the lancet from its retracted position to its extended position is effected with such force that contact of the moving lancet tip with the skin of a patient results in the piercing of the skin of the patient. In many such lancet devices having a movable lancet, the lancet is automatically drawn back into the body after reaching its extended position (e.g., using a spring) in order to minimize the risk of inadvertent lancet sticks.
Lancing instruments of the type described above are commonly used to lance dermal tissue. However, it has been found that, in certain situations, blood does not readily emanate from the wound site in the lanced skin. Rather, after puncturing the skin, conventional lancing devices are typically laid down onto a flat surface and, in a subsequent step, the user pinches, squeezes and/or kneads the dermal tissue surrounding the wound site in order to express out an adequate blood sample which can then be collected and analyzed for testing purposes.
As can be appreciated, it has been found that the aforementioned process for collecting a blood sample has a number of significant shortcomings.
As a first shortcoming, the aforementioned process is rather complex and requires a considerable level of manual dexterity. Specifically, the fact that the user is required to lay down the lancing instrument in between the lancing and blood expression processes, renders the aforementioned process somewhat difficult for many people (e.g., elderly patients) to perform, which is highly undesirable.
As a second shortcoming, the aforementioned process may introduce contaminants onto the lancing instrument. Specifically, in those situations where a lancing instrument is to be used for multiple lancing operations, the user must ensure that the lancing instrument is placed on a clean storage site after the lancing procedure but before commencing the blood expression process. If the lancing instrument is not placed on a sterile surface, the user subjects him/her self to potentially harmful contaminants when performing future lancing operations using the same lancing instrument, which is highly undesirable.